1. Field of the Invention
The present invention relates to means for lifting or supporting modular furniture of the type used in offices. The most common use for the apparatus is to allow access to an office floor, e.g. for replacement of carpets or other flooring, including panels of raised flooring, without the need to remove the furniture from the office. However, there may also be a need to lift panels to modify base portions of the panels.
2. Prior Art
Modern offices are often provided with so-called xe2x80x9cmodular furniturexe2x80x9d, which comprises an arrangement of panels interconnected at angles to form office dividers, and which have so-called xe2x80x9changing tracksxe2x80x9d used to support desks, bookshelves, and other necessary office equipment. These hanging tracks are vertical metal strips, usually located at the edges of the panels, having a series of undercut slots from which special hangers, with suitable hooks, can be suspended. Generally, these hanging tracks are aligned with feet which support the panels, and which usually provide the only contact between the floor and the modular furniture.
The fact that quite a number of such panels, and their associated desks and shelves, are connected together makes it time consuming and costly to dismantle this furniture and remove it from an office to allow carpeting or other flooring to be replaced. Accordingly, apparatus has been designed and used which will allow the panels and associated furniture to be temporarily raised so that new flooring can be placed underneath. Apparatus of this kind is described, for example, in:
U.S. Pat. No. 5,261,643, issued Nov. 16, 1993 to Wurdack;
U.S. Pat. No. 5,299,779, issued Apr. 5, 1994 to Collins;
U.S. Pat. No. 5,385,335, issued Jan. 31, 1995 to Wurdack;
U.S. Pat. No. 5,490,757, issued Feb. 13, 1996 to Stratman;
U.S. Pat. No. 5,529,287, issued Jun. 25, 1996 to Pelosi, Jr. et al.; and
U.S. Pat. No. 5,628,610, issued May 13, 1997 to Stratman et al.
Several of these patents use lifting jigs which have plates with a series of hooks for engaging the hanging tracks of the panels; for example the Wurdack patents, and those of Stratman and Pelosi et al. have this feature. Applicants have found that the arrangements shown in some of these patents tend to lack the desired stability, since they positively engage only a relatively short length of the hanging track, typically 2 to 5 inches of the hanging track.
Another drawback of these arrangements is that in some makes of panel, notably those made by Haworth Inc., the hanging tracks may be dislocated if the panels are lifted in this way.
Our Canadian Patent No.2,223,736, granted Mar. 30, 1999, and corresponding U.S. Pat. No. 5,947,449, issued Sep. 7, 1999, describe a lifting jig suitable for the Haworth type panels, or any such panel which cannot be lifted by their hanging tracks. The jig includes a lower portion having a support plate suitable for engaging the underside of a panel, and an upper, stabilizer portion having a hook with a downwardly facing undercut recess for engaging the bottom of one of the hanging track apertures, with the spacing between the hook and the support plate being adjustable so as to positively lock the jig in relation to the hanging track of the panel.
Other designs of lifting device suitable for Haworth type panels are shown in some recent patents, notably:
U.S. Pat. No. 5,855,360, issued Jan. 5, 1999 to Wurdack; and
Can. Pat. Appln. No.2,277,153, published Jul. 16, 1998, and assigned to Shaw Industries Inc.
The Wurdack ""360 patent is concerned with a lifting member specifically suitable for the Haworth type panels, and is not readily adaptable to panels which are better lifted by the hanging tracks.
The Shaw Industries Canadian application shows a lifting jig which can have various different attachments depending on the type of panel to be lifted, including platform members which can be used for Haworth type panels, and various hook type arrangements including hook plates which are situated side-by-side for simultaneously lifting the ends of adjacent panels. However, neither the Wurdack U.S. ""360 patent, nor the Shaw Industries application, show lifters for Haworth type panels which provide the kind of stability given by our patented design referred to above. In particular, none has a support plate which can be adjusted relative to a downwardly facing hook so that the spacing between the hook and the support plate allows the hook to enter an aperture in a hanging track at one spacing and allows the track to be positively gripped between the support plate and the hook at another spacing.
It is an object of the present invention to provide a lifting jig for lifting office panels which has all the advantages of that of our aforesaid U.S. and Canadian patents, and which is also easily adapted to lifting suitable panels by engagement of hooks with hanging tracks. In the preferred form, the lifting jig can simultaneously engage two hanging tracks at adjacent ends of two panels.
The present invention firstly provides apparatus for lifting or supporting modular furniture which can be used to provide a support plate fitting underneath a panel of the Haworth type and holding such panel more stably than prior art apparatus, in similar manner to the lifting jig of our aforesaid patents, and which can also easily be changed to provide upwardly opening hooks to engage a hanging track like those of the prior art patents.
The invention also provides a lifting jig which can simultaneously support adjacent hanging tracks of two panels while in effect locking the two hanging tracks together.
The present invention is similar to that of our aforesaid patents in being of the type having a support with a shaft which normally extends vertically and a lifting jig which is movable vertically on the shaft by jacking means, with the lifting jig comprising:
a main portion having a front face,
a lower portion having a support plate which projects from below said front face and which is suitable for engaging the underside of a panel, and
means for adjusting the position of the support plate relative to said main portion.
In accordance with this invention, a hook plate in the form of an angle bracket is mounted on the front face of the lifting jig main portion, the angle bracket having an inner flange parallel to and attached to the said front face and having an outer flange projecting perpendicularly from the said front face and having hook means for engaging in a hanging track of one of the panels so as to positively locate the jig in relation to the panel. The angle bracket has its inner flange provided with several slots which extend normally horizontally, the slots being engageable by screws which extend into said front face to attach the inner flange to the main portion of the lifting jig and which allow lateral adjustment of the bracket relative to the lifting jig and to the support plate. These slots have enlarged portions which allow heads of the screws to pass through these enlarged slot portions so that, with suitable manipulation, the bracket may be removed from the lifting jig upon loosening of the screws but without removal of the screws, and may be repositioned in inverted orientation.
With this arrangement, the angle bracket or hook plate may be fixed by the screws in a first orientation in which the hook means are downwardly open and suitable to secure a hanging track of a panel while the panel is being lifted by the support plate and has parts of its hanging track gripped between the support plate and the hook means, and, upon loosening of the screws, the bracket can be removed from the lifting jig and reattached to the jig by the screws in an inverted orientation in which the hook means are upwardly open for engaging and lifting the hanging track of a panel.
The angle bracket is preferably attached to the front face by at least three screws, and to allow for this re-orientation the screws and slots all have equal spacing between them.
It may be noted that the possibility of fitting the hook bracket in two relatively inverted positions is not available in the prior art Shaw Industries application, since if the Shaw Industries hook plate were to be inverted and inserted into the hanging track it would tend to fall out.
As in our issued patents, the hook means is considerably narrower than the shaft so as to be suitable for engagement in a hanging track, and the spacing between the hook means and the support plate is adjustable so that when the support plate is being used the hook means can enter an aperture of the hanging track at one spacing and the hanging track can be positively gripped between the hook means and the support plate at another spacing.
The bracket may be one of a pair of brackets which each have at least one slot which extends horizontally and which each have a series of the hook means, the slots allowing adjustment of the lateral spacing of the hook means of the two brackets, whereby the hook means can be engaged in the adjacent hanging tracks of two joined panels and provide a means for locking together the adjacent hanging tracks of the two panels. The brackets may include a first, relatively long bracket having two longitudinally spaced apart rows of hooks giving good stability for holding a panel, and a relatively short bracket having a single row of hooks.